(1) Field of the Invention
The present invention relates generally to a benthic microbial fuel cell and, more particularly, relates to a readily deployable microbial fuel cell, which may be towed into position by cable for deployment on a sea bottom without the need for divers.
(2) Description of Prior Art
A simple Benthic microbial fuel cell (BMFC) system consists of an anode, a cathode and an intermediate electrical circuit. Both the anode and cathode are typically made from carbon or graphite. The anode electrode is buried in the marine sediment to a depth sufficient to sustain anaerobic microbial activity. This step is time consuming and costly. A cathode is also located in the ocean water, usually immediately above the buried anode. Electrical wires connect the anode and cathode to an intermediate electrical circuit that may boost the voltage and store electrical energy or operate an underwater electrical device. The BMFC system generates electrical power by oxidizing sediment organic matter and simultaneously reducing oxygen dissolved in the overlying water as discussed below, e.g., in U.S. Pat. No. 6,913,854. This process generates a sustainable voltage gradient that can be used to generate electrical power.
Prior art microbial fuel cells have disadvantages. Previous systems required divers to install graphite plates in the marine sediment. As noted above, this is a costly and time consuming process. In addition, the graphite plate electrodes are delicate and difficult to handle during an undersea deployment.
The following U.S. Patents describe various prior art systems that may be related to the above and/or other microbial fuel cells:
U.S. Pat. No. 5,288,564 to Klein et al., issued Feb. 22, 1994, discloses a battery including a plurality of series connected battery cells rolled into a cylindrical form. Each of the battery cells includes a thin flexible rectangular anode closely spaced apart from a thin flexible cathode. The plurality of series connected battery cells are placed on a flexible carrier sheet which is tightly wound into the cylindrical form.
U.S. Pat. No. 5,424,147, to Khasin et al., issued Jun. 13, 1995, discloses a water-activated, deferred-action battery having a housing containing at least one cell, comprising at least one anode selected from the group consisting of magnesium, aluminum, zinc and alloys thereof; a cathode comprising a skeletal frame including conductive metal and having a portion of its surface area formed as open spaces, and further comprising a heat-pressed, rigid static bed of active cathode material encompassing the skeletal frame. The cathode material is formed of cuprous chloride, sulfur, carbon and a water-ionizable salt and being compacted and fused under pressure and heat to itself and to the skeletal frame, to form a heat-fused, conductive, electrochemically active phase. At least one cavity separates the cathode and the at least one anode, and at least one aperture leading to the at least one cavity for the ingress of an electrolyte-forming, aqueous liquid.
U.S. Pat. No. 5,427,871, to Garshol et al., issued Jun. 27, 1995, relates to galvanic seawater cells and batteries and in particular to cathodes which are suitable for use in galvanic cells that use an oxidant dissolved in the electrolyte as depolarizer. An example of such cells are seawater cells which use the oxygen dissolved in the seawater as oxidant. The cell has an inert electrode which consists of a number of conducting fibers connected to a conducting body. The fibers have different orientations relatively to each other and to the body. The electrode body consists of two or more wires which are twisted together to constitute an electrode stem while clamping the fibers in a fixed position between the wires, as in a laboratory bottle brush.
U.S. Pat. No. 6,379,835, to Kucherovsky et al., issued Apr. 30, 2002, discloses a flexible thin film battery including a film layer and a porous cathode deposited on a portion of a film and a porous anode deposited on a portion of the film, with an electrolyte and separator layer positioned between the porous anode and the porous cathode. The electrolyte is preferably dried so the battery is activated when liquid contacts the electrolyte and separator layer. Water swellable particles are included in the cell. The film layers are least partially sealed around the edges, confining the anode, cathode, and electrolyte and separator layer. The method of producing such a battery preferably includes printing various inks in a pattern on a polymeric film.
U.S. Pat. No. 6,913,854, to Alberte et al., issued Jul. 5, 2005, discloses a method and apparatus for generating power from voltage gradients at sediment-water interfaces or within stratified euxinic water-columns. Natural voltage gradients typically exist at and about sediment-water interfaces or in isolated water bodies. One electrode (anode) is positioned in the sediment or water just below the redox boundary and the other electrode (cathode) is positioned in the water above the redox boundary over the first electrode. The anode is lower in voltage than the cathode. Current will flow when the electrodes are connected through a load, and near-perpetual generating of worthwhile power may be sustained by the net oxidation of organic matter catalyzed by microorganisms.
U.S. Pat. No. 7,550,224, to Tender et al., issued Jun. 23, 2009, discloses an apparatus having a metallic manganese anode; a cathode capable of reducing at least one species found in marine water; and a rig coupled to the anode and the cathode capable of maintaining the anode below a marine sediment surface and maintaining the cathode above marine the sediment surface. A method of generating power by: positioning in marine sediment a metallic manganese anode; positioning in marine water a cathode capable of reducing at least one species found in marine water; and connecting electrical leads between the anode, the cathode, and an electrical load.
United States Patent Application 2010/0081014, to Robert Tyce et al., issued Apr. 1, 2010, discloses a microbial fuel cell power system based on a microbe-based fuel cell such as a benthic microbial fuel cell (BMFCs). In accordance with the present invention, one or more BMFCs can be connected to one or more batteries such as a nickel metal hydride (NiMH) or sealed lead acid (SLA) battery and can be used to charge the batteries for long-term persistent underwater use. At any time, some of the connected batteries are being charged by the BMFC, while the others are being used to power a connected device. By using electrically isolated fuel cell converters, the batteries can be charged while in circuit. With non-isolated converters, pairs of batteries can be switched between offline charging and online discharging. The battery system can be controlled by a control system that comprises a microcontroller that periodically measures system voltages and currents, swaps the batteries being charged, and records the system results for post-mission analysis. The batteries can be connected to an underwater monitoring system such as the Acoustic Doppler Current Profiler (ADCP) or Shallow-Water Environmental Profiler in Trawl-Safe Real-Time Configuration (SEPTR) systems used by the U.S. Navy and can provide long-term persistent power supplies to such systems.
The above discussed prior art does not address solutions provided by the present invention, which teaches a more easily deployed microbial fuel cell configuration.
Consequently, those skilled in the art will appreciate the present invention that addresses the above described and other problems.